The objectives are to characterize two new observations: 1) Granulocyte function is altered (increased granulocyte adherence) in patients with psoriasis and psoriatic arthritis. Preliminary evidence indicates that this is the result of a serum factor. 2) Increased C1q binding, representing circulating immune complexes, occurs in the serum of these patients. Clq binding exhibited a strong positive correlation with granulocyte adherence. Disease control studies will be made in contact dermatitis, ultraviolet phototoxicity, and subacute cutaneous lupus erythematosus. Longitudinal studies will determine the temporal relationship betweem disease activity and tests of neutrophil function (in vitro: granulocyte adherence, random migration, chemotaxis and NBT reduction) (in vivo: neutrophil emigration). The serum factor(s) responsible for increased granulocyte adherence will be characterized. In an animal model of altered neutrophil function, neutrophil activities will be tested in vivo to determine the effect of such alterations on neutrophil participation in cutaneous inflammation. Increased Clq binding in psoriasis will be characterized by: 1) evaluating a large sample of patients manifestations, 2) utilizing two additional in vitro tests for circulating immune complexes: Raji-cell immunofluorescence and monoclonal rheumatoid factor precipitation, 3) assessing with immunofluorescence techniques both internalized and surface bound immunoglobulins on neutrophils, and 4) confirming the strong positive correlation between granulocyte adherence and Clq binding. These studies will extend the understanding of immunologic abnormalities recognized in psoriasis to include altered neutrophil function and circulating immune complexes. The ultimate objective is to offer new approaches to the treatment of psoriasis and psoriatic arthritis.